# Copyright 2016 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

use strict;
use warnings;

package fibonacci;

sub fibonacci {
  my ($n) = @_;
  
  if ($n < 2) {
    return $n;
  }
  
  my $n1 = 0;
  my $n2 = 1;

  for my $i ( 2 .. $n ) {
    my $sum = $n1 + $n2;
    $n1 = $n2;
    $n2 = $sum;
  }
  
  return $n2;
}

1;